Of course, says the industry. Of course not, say scientists such as Dr. Milton Zaret, who discovered the relationship between microwave radiation and cataracts.

How much this continuing controversy has affected the sales of a very expensive kitchen gadget is impossible to determine. Some retail appliance stores acknowledge, as one owner said, that "fear of radiation dangers is holding a lot of folks back."

This kind of statement infuriates manufacturers who insist that microwaves are absolutely safe. "There has never been a fatality connected with the use of microwave ovens," said Jane Pazlar, customer service manager for Litton Industries.

On the other side is Dr. Zaret, associate professor of clinical ophthalmology at New York University Medical Center and one of the foremost opthalmological surgeons in this country. Dr. Zaret says the ovens aren't safe at all "because they are permitted to leak."

In between these opposing points of view are those admittedly unsure about the safety of the 8.9 million microwave ovens that have been sold since 1972. Forecasts are for sales of almost 3 million more this year.

Susan Freeman, assistant to the president of Microwave Cooking Etc., a chain of stores that sells ovens and offers classes in their use, paused before she answered the question. "Let me hedge," Freeman said. "I feel that from all the information I have read, I find no reason to believe they are not safe."

But one of the authors of a government report on microwave radiation says he would not have the appliance in his home. Stuart Fleschman, who worked on the Government Accounting Office report, "More Protection From Microwave Radiation Hazards Needed," said, "I guess I'm conservative. Certainly some studies show the effects are cumulative. It's kind of tough to deal with because so little is known. Most people who look seriously at the area are concerned because no one knows if there is a safe threshold."

Fleschman went on to say that he really doesn't feel there is a health hazard if the ovens meet government standards, "but I wouldn't have an oven, just because so little is known."

Those standards are set by the Food and Drug Administration's Bureau of Radiological Health (BRH), and they are based on occupational guidelines for exposure set more than 20 years ago. The man responsible for them, Herman Schwan, a professor at the University of Pennsylvania's school of engineering, told a 1968 Senate hearing the standards were "the best we can formulate on the basis of presently available knowledge." He acknowledged that they had been "crudely set" -- and "badly need refinement."

In fact, there are two set of criteria for microwave radiation. The standard that is for exposure to microwave radiation is, in microwave language, 10 milliwatts per centimeter square (10 mW/cm2).

Dr. Schwan has not changed his mind. "A good deal of recent evidence suggests we should lower that standard to 1 milliwatt," Schwan said on the phone last week.

FDA's standards for microwave emission from ovens is based on the 10 milliwatt figure. The agency has set the emission standard, which is taken 2 inches from the oven, at 1 milliwatt before the oven is purchased and 5 milliwatts after its sale. The farther one stands from the oven, the less the exposure. A 1976 FDA report, which analyzes General Electric's unsuccessful attempt to contest the agency's recall of some 36,000 ovens leaking above the standards, puts this in some perspective. In order to maintain exposure below the level considered safe for workers in the Soviet Union, one must remain four feet from an oven emitting 5 mW.

Schwan, who was paid by General Electric as a consultant to testify at those hearings, says he is not concerned with the safety of microwave ovens because the emission standards are "pretty well enforced." But Fleschman said the "5 milliwatt standard is not based on any hard information."

Referring to the occupational guideline for exposure, Fleschman said: "From what I saw, I don't know how they can determine that 10 is a safe level. A number of studies have raised questions about the safety at less than 10."

Dr. Zaret, who was one of the first to establish the relationship between microwave exposure and cataracts while doing research for the armed forces, calls the 5 mW levels "a lot of baloney." The first assumption they used, said Zaret, referring to the 10 mW exposure level, is not "based on any science. All the Bureau of Radiological Health has done is set a performance standard for the oven. It means how badly an oven can malfunction before they can say it is unsafe. That's quite different from finding out what is safe from chronic repeated usage over a long time."

Says Paul Brodeur, author of "The Zapping of America" and a journalist who has become an expert on microwave radiation: "If microwave radiation were a food additive or drug under the laws of our land, it would be banned."

Alan Anderson, chief of standards support staff at the Bureau of Radiological Health, acknowledges that scientists "don't know all the answers about chronic use in the home." Another BRH scientist, referring to the current FDA standard, puts it more strongly: "The standard was arbitrary and capricious."

Industry emission standards are lower than the government's. According to a Litton Industries vice-president, Verle Blaha, "We use about sixtenths milliwatts as an internal factory standard that doesn't change." He says the design of the microwave oven has "advanced to the point where there is no longer a concern for wear or transportation damage." (Brodeur took exception to that statement: "Would you," he asked, "believe a car salesman who told you that the car door will never leak air?")

"There is no meaningful standard," Dr. Zaret said, because no one knows what levels of radiation cause "cataracts, retinal diseases and other eye pathology.Every organ system can be effected."

Part of the problem is lack of long-term studies. The radiation that comes from microwave ovens is only part of the radiation to which people are exposed every day. In one form or another, it comes not only from the sun but from radio signals, television antennae, diathermy machines, certain kinds of smoke detectors -- and exposure levels increase every day.

According to the GAO report: "As the level and duration of microwave exposure increases, the possibility that there will be biological effects also appears to increase. Repeated exposures to microwave radiation at a given level have been reported to cause biological effects when a single exposure at the same level did not."

Some of the studies considered by GAO were on animals exposed to levels as low as .0006 mW. Changes were noted in behavior of the nervous system, the blood system and genetic functions. Twenty-two human studies were examined by GAO. Exposure levels ranged from .01 mW to 20 mW. Four studies reported no effects and 18 reported effects observed on the eyes, heart, nervous system or blood system.

One of the most recent investigations was conducted by Dr. Guy and Dr. Richard Lovely at the University of Washington, who irradiated rabbits at .5 mW and noted "statistically significant changes." According to Dr. Lovely, there was a "significant shift in the sodium and potassium levels," the sodium increasing, the potassium decreasing.

Asked if that might be a sign of hypertension, Dr. Lovely said: "Yes. As a matter of fact, if we had known we were going to find that we would have taken the animals' blood pressure."

Despite the accumulating evidence, FDA recently put out a fact sheet for prospective microwave-oven purchasers that says: "To ease your mind about safety, FDA requires that all microwaves manufactured since 1971 meet a performance standard that assures their safety."

It does however, hedge its bets. Further on FDA admits the effects of microwaves on people are "still under study."

Some manufacturers recommend operating a microwave oven at arm's length. Yet children often press their noses right up against the glass to see food cooking. People frequently lean on the ovens, which are not hot to the touch, while they are operating. It is not at all unusual, when a microwave is below the burners on a stove, to stand in front of the microwave oven, while it is on, stirring a pot.

Susan Freeman from Microwave Cooking Etc. says, "It's dumb for kids to press their noses against oven doors. FDA has not found that it can hurt you, but they advise you not to do so. Pregnant women shouldn't stand close either. They have not found that it will hurt you, but they advise against it."

The Bureau of Radiological Health says, "The fetus is probably the most sensitive segment of the population potentially exposed to microwave radiation."

But even Dr. Zaret admits there can be safe microwave ovens. "If they don't leak, they are safe." But how could you know? "That's the big question. No one can tell you. None should be permitted to leak."

Asked if it is possible to produce a microwave oven emitting zero detectable levels of radiation, Litton's Blaha said: "It's technically impossible to set it at zero. We haven't spent $50 billion developing that instrumentation. You can continue to develop instrumentation that will do it, but pursuing it further would be of no value."

That may depend on what is meant by value.

In FDA's analysis of the GE recall case the agency said: "The possibility that cumulative effects of microwave radiation can occur has been raised through research and cannot be ignored. The potential exisits for exposure of young and very young people repetitively as ovens come into common usage, and effects may result. Substantial follow-up studies of exposed populations will be needed to examine the question of such effects."

Commenting on the last sentence, Paul Brodeur asked: "Can FDA really be saying that people exposed repeatedly to the radiation leaking from microwave ovens may, in effect, be test animals in a vast biological experiment whose results will only be known at some future date?"